1. Field of the Invention
This invention relates to arrangements for supporting drums. In particular, the invention relates to arrangements for supporting drums such as rotary kilns, tube mills and the like.
2. Description of the Prior Art
Tube mills are generally supported by ring-like members known in the art as "live rings." Certain arrangements may include one ring near each end of the drum with each cooperating with two corresponding supports. Another arrangement utilizes a single live ring with two supports at one end, the other end being supported by means of a mill trunnion resting in a bearing.
Rotary kilns, like tube mills, may be supported by means of a live ring at both ends, but as a rule their length in relation to their diameter is so great that they have to be supported at several points. For example, in some arrangements live rings have been positioned at from three to six positions along the drum. In addition, it can be seen that the rotary kiln is further distinguished from the tube mill in that the temperatures occurring in the kiln are higher than those existing in the tube mill. Thus, temperature dissipation is not as critical in the tube mill.
Each support corresponding with a live ring or other running surface may be either stationary or movable. An example of a stationary support is the type known as "slide shoe." The movable type is usually in the form of one or more rollers. Both types of support arrangements have associated disadvantages which are substantially avoided by my invention.
One disadvantage is concerned with lubrication and occurs particularly where the live ring rotates in slide shoes. The temperature of the drum and, consequently, of the live ring may be so high that the lubricating ability of the oil is reduced or even destroyed. When the drum is a rotary kiln this problem has become of increasing importance. In particular, in recent years, due to increased kiln dimensions the temperatures of the kiln shell and, consequently, of the live ring have been reaching a higher level than previously experienced. In addition, where live rings cooperate with slide shoes a careful surface finish is required. Thus, the live ring and its cooperating slide shoes must, therefore, be effectively protected against accumulating dust and impurities. This problem has resulted in the provision of extensive casing with sealing means surrounding the live ring and the adjacent drum section, as well as the supports. The necessity for such additional casing particularly emphasizes the disadvantages of the arrangements of the prior art.
Where rollers are used instead of slide shoes, an effective lubrication between the roller and live ring may be difficult to provide owing to the high temperature of the live ring. This is particularly so in the case of rotary kilns because of the higher temperatures occurring in these "drums" as previously mentioned. Because of the increasing kiln dimensions which have resulted in these supporting rollers becoming of such large dimensions, it is clearly desirable to find other solutions than these traditional, heavy constructions. In addition, the heavy supporting rollers now being used present constructional problems such as shrinking of the journals into the rollers, that only few manufacturers are capable of casting the large charge of steel which is generally required in the manufacture of these heavy supporting rollers. Apart from this, there are obvious economic advantages in limiting the consumption of available steel having the high quality required in such supporting rollers. Accordingly, my invention provides a solution which simultaneously relieves, or at least reduces, the three major problems hereinbefore mentioned. The present invention avoids the problems of lubrication, of keeping the dirt and impurities away from the contacting surfaces, and of reducing the weight of the supports, particularly where rollers are utilized.